A. Field of Invention
Embodiments according to aspects of the present invention generally relate to systems and methods for lighting. In particular, embodiments of the present invention relate to systems, methods, and apparatus for lighting sports venues.
B. Background
Sports fields for baseball, football, or other sporting events may be lit by artificial light in order to allow game play at night. In order to do that, evenly distributed lighting is required on the playing field and in the space above the playing field. The lighting is typically concentrated on the ground to allow the actions of the players and the movements of the ball in play within the ‘ground zone’ to be easily seen by players and spectators. Above the ground zone is a three-dimensional space which may be called the ‘fly zone.’ The ball is sometimes in play in the fly zone. Lighting is often provided to the fly zone; often as a byproduct of lighting the ground zone.
Light may be provided to the fly zone by intentionally aiming lights up into the fly zone. Or, light may be provided to the fly zone simply as the result of poor control of lights aimed at a playing field. In these cases, sufficient light may be provided to the fly zone by fixtures with limited directional control of light. However, this can result in excess uplight or “sky glow”, spill light, and glare for the duration of the event.
Lights which are high enough and which have a high enough aiming angle (i.e., a large enough angle as measured from nadir or straight down from the fixture) may provide some light in at least the lower fly zone, however, this type of lighting is often not sufficient to illuminate at least some portion of travel of a ball that is in play (such as a high fly ball in baseball or a punt or kick in football). Or, it may provide an adequate level of light, but may again contribute to a high level of unwanted light outside and/or above the playing area for the duration of the event. Thus there is room for improvement in the art.
As lighting technology continues to improve, more precise aiming and focusing of lighting on the ground zone results in less on-field glare as well as less undesired uplight, spill, and general glare. Unfortunately, this normally reduces availability of light in the fly zone with the result that more of the fly zone is dark. Attempts to overcome this by intentionally directing some of the light from the fixtures to the fly zone, can result in returning to problems of excess uplight, spill, and glare, as well as increasing energy costs. Further, commonly used HID (high intensity discharge) lights require a warm-up period of several minutes before providing usable light. Thus it is impossible to use conventional lights for intermittent lighting. In the case where these lights are used for intentional illumination of the fly zone, the lighting must be provided to the zone for the duration of the game, even though the light is needed only when the ball is high in the air (which is a relatively small and generally unpredictable percentage of the duration of the game).
It may be seen therefore that efforts to aim lighting more precisely at the field and to reduce uplight, spill, and glare are at cross-purposes with the need to illuminate the ball during the times it is in the fly zone. Thus, there is need for improvement in the art by providing light to the fly zone without significantly adding to uplight, spill and glare, and without requiring such lighting to be on for the duration of the game.
It is therefore apparent that lighting that provides efficient momentary uplighting that is precisely aimed to avoid glare and spill issues and that does not contribute significantly to sky glow or other unwanted conditions is desirable in the industry.